Improved reliability single loop single feed 7T SRAM cell for biomedical applications

Abstract

Portable biomedical devices are born to reach a maximum number of people at an effective cost, and because of their small size and battery operation, the impact of portable medical devices is huge. For biomedical image processing devices, it is very important to store pixel information in embedded memory, because pixel values contain critical information about the image. For this critical information storage, most embedded memories consist of static random access memory (SRAM). SRAM, which stores critical information must have a high level of stability and reliability with low power dissipation. This paper proposes a single loop single-feed 7T (SLSF7T) SRAM cell that operates in the sub-threshold region (reducing the supply voltage to reduce power dissipation) and attains a high read static margin. To evaluate the read-and-write stability of the SRAM cell, the N-curve method is adopted in this work.

The proposed SLSF7T SRAM cell design offers several improvements over existing Biomedical Transmission Gate 8T (BT8T) and 9T SRAM cells. Specifically, the SLSF7T SRAM cell design shows an increase in static voltage noise margin (SVNM) by 75.86% and 75.34%, reduction in delay by 37.86% and 58.52%, and also offers less leakage power dissipation by 72% and 23.29% as compared to the BT8T and 9T cells, respectively. Along with the low power and high stability, the other most significant feature of the proposed work is its area efficiency because the proposed memory cell only consists of 7 transistors, it requires only 1.1X area overhead compared to the conventional 6T memory cell. The calculated performance matrix of the proposed cell is the highest among the considered SRAM cells for compression. The proposed cell operates in the sub-threshold region and achieves the best performance parameters for memory design for biomedical devices and applications at a 300 mV supply voltage.